Various types of multi-patterning photolithography techniques can be utilized to manufacture semiconductor integrated circuits. Such multi-patterning techniques include sidewall image transfer (SIT), self-aligned doubled patterning (SADP), and self-aligned quadruple patterning (SAQP) techniques, for example. The current SIT, SADP and SAQP methods utilize deposition and etch back processes to create uniform memorization and transfer elements. In particular, these techniques involve spacer patterning steps in which spacers are formed on the sidewalls of sacrificial features (e.g., sacrificial mandrels), wherein the sacrificial features are removed to leave a pattern of spacers which is used to etch features into an underlying layer at sub-lithographic dimensions. One type of SADP method, referred to as spacer-is-dielectric (SID), utilizes the spacers (not sacrificial mandrels) to define dielectric spaces between target features (e.g., metal lines). This is in contrast to other SADP methods in which the spacers define the conductive features (metallization), and wherein an extra cut mask is needed to cut the portions of the spacers which wrap around the end portions of the mandrels to avoid forming conductive loops.
SID SADP techniques are commonly utilized in back-end-of-line (BEOL) process flows for fabricating a metallization level comprising an array of parallel metal lines with uniform widths (e.g., minimum width—1X) and spacing. However, in some metallization levels, wider wires (e.g., greater than 1X) are desired to implement power rails, clock networks, analog wires, etc. The formation of wider wires (greater than minimum width 1X) can be supported in SADP with severe limitations. For example, in a SID SADP process flow, the spacer width is fixed, while mandrel assigned feature width and non-mandrel assigned feature widths can be modulated to pattern wider wires. However, the insertion of a single wide wire in an array of uniform wide wires requires a pair of wide wires to align the mandrel/non-mandrel assignment. Furthermore, wider mandrel shapes present a challenge to the lithography fidelity of adjacent 1X-width features.